The present invention relates to an electrochromic element to be used in the control of luminous energy and in a display, and particularly to a liquid type electrochromic element.
The phenomenon that an electrolytic oxidation or an electrolytic reduction reversibly occurs upon applying a voltage to be reversibly colored or discolored refers to electrochromism. An electrochromic (hereinafter sometimes referred to as xe2x80x9cECxe2x80x9d) element utilizing such a phenomenon has been used in an element for regulating luminous energy (e.g., an antiglare mirror, a dimmer glass, and a meter, a brightness control element, e.g., an EL display element), number display utilizing a segment, and a display element such as an electrochromic display. Depending upon the state of EC layers constructing the EC element, the EC element can be roughly divided into a liquid type, a whole solid type, and the like. Amongst them, the liquid type EC element is that at least part of the EC layers should be composed of a liquid or a gel.
FIG. 7 shows a configuration of a typical liquid type EC element. Outlining the configuration, a lower glass substrate 1 having a lower electrically conductive film 3 and an upper glass substrate 2 having an upper electrically conductive film 4 are adhered by a sealing portion 5 in such a manner that the electrode films 3 and 4 reside in inner positions, respectively, and an EC solution 6 is injected and incorporated from an inlet for introducing an EC solution inlet (not shown) provided on a part of the sealing portion 5.
Upon applying a voltage between the lower electrically conductive film 3 and the upper electrically conductive film 4 of the EC element thus produced, an electrochemically reaction occurs within the EC solution 6, which is a chromic layer, to thereby color the element. Upon applying a voltage in the direction reverse to the coloration, the reverse reaction occurs to discolor the element.
In order to provide tapping electrode portions for connecting the lower electrically conductive film 3 and the upper electrically conductive film 4 to external wires, respectively, as shown in FIG. 8(1), these two glass substrates 1 and 2 each having an electrically conductive film are shifted with each other in a vertical direction shown in this figure; or as shown in FIG. 8(2), they are shifted with each other in an inclined direction shown in this figure. The exposed portions having width W1 and W2 are used as tapping electrode portions 1a and 1b, respectively, and the portions of the electrically conductive film portions exposed on the tapping electrode portions 1a and 1b are taken as tapping electrodes. Alternatively, as shown in FIG. 8(3), tapping electrodes are provided by changing the sizes of two glass substrates 1 and 2 each having an electrically conductive film (Japanese Patent Laid-Open No. 61-129626, Japanese Patent Laid-Open No. 63-249826, Japanese Patent Laid-Open No. 61-190528, and U.S. Pat. No. 5,668,663). The reason why the substrates are shifted with each other is that since the distance h shown in FIG. 6 between the substrates is practically very narrow in the EC element, it is difficult to be connected to the external wire, and particularly, it is not possible to fit a clip electrode etc. to the substrates provided vertically unless the substrates are shifted.
However, in such configurations as described above, the tapping electrode portions must be provided on at least two sides of the liquid type EC element. Since peripheral portions including the tapping electrode portions and the sealing portion are not an effective area, the providing of the tapping electrode portions on two sides unduly enlarges the areas of the tapping electrode portions and, thus, it is not preferable in terms of the ratio of the effective area. In the case where the peripheral portions including the tapping electrode portions and the sealing are required to be covered with a frame or such, if the areas of the tapping electrode portions are large, the area for covering the tapping electrode portions becomes large accordingly, which is not preferable in terms of appearance. In particular, in an electrochromic mirror for providing an automobile or such, the thickness of mirror ring (frame edge) covering the outer circumference of the mirror becomes large, which undesirably gives heavy impression.
In the present invention, since the tapping electrode portions are provided on one side of the liquid type EC element, the effective area of the liquid type EC element during the coloration and discoloration can be enlarged. By intensively arranging the tapping electrode portions on one side, the wiring becomes easy and the length of the wire can be shortened.
For example, in the case of the automobile antiglare mirror, the effective area for the mirror portion is increased to widen the effective view field, contributing the safety. What is more, a mirror ring which covers the outer circumference of the mirror can be made slim, enhancing a smart looking from the viewpoint of the design. Also, in comparison with the case where electrodes are tapped on two or more sides, the present invention makes it possible to secure the same effective view field with a lightweight.
Also, for example, if the EC element of the present invention is used for controlling the brightness of the luminophor element, by intensively arranging the tapping electrode portions on one side, the electrode can be tapped only within a restricted space, making it possible to control the brightness of luminophor element which requires the tapping of the electrode only from one side (such as meters and EL display elements), such a control being difficult in the prior art techniques.